1. Field of the Invention
Embodiments of the present invention generally relate to a casing tester for plugging and abandoning a wellbore.
2. Description of the Related Art
FIG. 1A is a cross section of a prior art sub-sea wellbore 5 drilled and completed with a land-type completion 1. A conductor casing string 10 may be set from above sea-level 15, through the sea 20, and into the sea-floor or mudline 25. The conductor casing 10 provides for mud-returns and allows the wellhead 30 to be located at sea-level 15 rather than on the sea-floor 25.
Once the conductor casing 10 has been set and cemented 35 into the wellbore 5, the wellbore 5 may be drilled to a deeper depth. A second string of casing, known as surface casing 40, may then be run-in and cemented 45 into place. As the wellbore 5 approaches a hydrocarbon-bearing formation 50, i.e., crude oil and/or natural gas, a third string of casing, known as production casing 55, may be run-into the wellbore 5 and cemented 60 into place. Thereafter, the production casing 55 may be perforated 65 to permit the fluid hydrocarbons 70 to flow into the interior of the casing. The hydrocarbons 70 may be transported from the production zone 50 of the wellbore 5 through a production tubing string 75 run into the wellbore 5. An annulus 80 defined between the production casing 55 and the production tubing 75 may be isolated from the producing formation 50 with a packer 85.
Additionally, a stove or drive pipe may be jetted, driven, or drilled in before the conductor casing 10 and/or one or more intermediate casing strings may be run-in and cemented between the surface 40 and production 55 casing strings. The stove or drive pipe may or may not be cemented.
FIG. 1B is a cross section of the completion 1 damaged by a hurricane. Hurricanes in the Gulf of Mexico have recently damaged or destroyed several production platforms (not shown) along with the completions 1. The production platforms and the completions 1 have sunk to the sea-floor 25. Many of the wellbores 5 had been in production for many years, thereby depleting the formations 50 such that the platform operators desire to plug and abandon the wellbores 5. To plug and abandon the wellbores 5, the annulus between the surface 40 and production 75 casing strings must be tested to ensure integrity of the cement 60 so that hydrocarbons do not leak into the sea 20 and/or sensitive non-hydrocarbon formations, such as aquifers.